The present invention relates generally to folding bed frame structures and, more particularly, to folding bed frames of the type specially adapted for opening and folding articulation from and into the enclosure of a sofa frame or the like.
Convertible sofa beds having widely varying folding bed frame structures are in common use. Characteristically, the folding bed frames of such sofa beds are provided with a plurality of bed sections pivotally connected in end-to-end relation and operatively associated with a linkage arrangement for mounting within the rectangular enclosure of a sofa bed frame defined by its side frame members, which normally comprise the sofa armrests, its sofa back and a front rail, to be articulable between a folded or retracted condition stored within the sofa frame enclosure and a horizontally extended condition disposed and extending outwardly from the enclosure over and beyond the front rail of the sofa frame.
Over the years, substantial activity has been devoted to the improvement of folding bed frame structures of this type. One improved feature which as proved to be popular and useful is the provision of the rear end or "head" section of a folding sofa bed frame structure with the ability to be raised into an inclined position independently of the other bed sections after the structure has been unfolded into its extended position. Such an inclined disposition of the head section is intended to raise the head and shoulders of the user into a convenient position suitable for viewing television, reading, etc., while reclined on the sofa bed. Hence, this feature has come to be commonly referred to in sofa bed frame structures as a "TV position." Representative examples of known constructions of sofa bed frames with the capability of such a TV position are U.S. Pat. Nos. 3,984,883; 4,035,852; 4,104,745; 4,200,941; 4,571,756; 4,669,134; and 5,257,424.
In the past, the mechanisms used to achieve such TV positioning have often been complicated and inconvenient to use, as well as sometimes proving to be unreliable in long-term operation. Most commercially available sofa bed frames with a TV position head rest are capable of establishing only a single TV position, which is not necessarily comfortable for all users. Also, such sofa beds typically require that the latching mechanism be disengaged manually to return the head section to a horizontal sleeping position before the structure can be folded back into the sofa frame for storage. Some efforts have been made to address these disadvantages. For example, U.S. Pat. No. 4,669,134 discloses a sofa frame structure whose head section is selectively positionable in two differently inclined TV positions. U.S. Pat. No. 4,571,756 discloses a sofa bed frame with an auxiliary TV position linkage associated with the head section of the structure, which is adapted to automatically disengage upon folding of the bed frame into its stored position.